02315nas a2200193   4500008004100000245010400041210006900145300001300214490000800227520163200235653002401867653001601891653001901907653001401926653001701940100001601957700002001973856012801993       1999                        eng d00aExotic plant species in a C4-dominated grassland: Invasibility, disturbance and community structure0 aExotic plant species in a C4dominated grassland Invasibility dis  a605 -6120 v1203 aWe used data from a 15-year experiment in a C4-dominated grassland to address the effects of community structure (i.e., plant species richness, dominance) and disturbance on invasibility, as measured by abundance and richness of exotic species. Our specific objectives were to assess the temporal and spatial patterns of exotic plant species in a native grassland in Kansas (USA) and to determine the factors that control exotic species abundance and richness (i.e., invasibility). Exotic species (90% C3 plants) comprised approximately 10% of the flora, and their turnover was relatively high (30%) over the 15-year period. We found that disturbances significantly affected the abundance and richness of exotic species. In particular, long-term annually burned watersheds had lower cover of exotic species than unburned watersheds, and fire reduced exotic species richness by 80–90%. Exotic and native species richness were positively correlated across sites subjected to different fire (r = 0.72) and grazing (r = 0.67) treatments, and the number of exotic species was lowest on sites with the highest productivity of C4 grasses (i.e., high dominance). These results provide strong evidence for the role of community structure, as affected by disturbance, in determining invasibility of this grassland. Moreover, a significant positive relationship between exotic and native species richness was observed within a disturbance regime (annually burned sites, r = 0.51; unburned sites, r = 0.59). Thus, invasibility of this C4-dominated grassland can also be directly related to community structure independent of disturbance.10acommunity structure10adisturbance10aexotic species10agrassland10aInvasibility1 aSmith, M.D.1 aKnapp, Alan, K.  uhttp://knz.lternet.edu/content/exotic-plant-species-c4-dominated-grassland-invasibility-disturbance-and-community-structure